<!DOCTYPE html>
<html>

	<head><link rel="shortcut icon" href="http://likexia.gitee.io/tools/lib/img/h5.png" type="image/x-icon">
		<meta charset="utf-8">
		<!--自动刷新，1s=1-->
		<!--<META http-equiv="Refresh" content="3">-->
		<!--<meta http-equiv="X-UA-Compatible" content="IE=7" />-->
		<meta http-equiv="X-UA-Compatible" cotent="IE=edge,chrome=1" />
		<!--禁止缓存-测试时用-->
		<meta http-equiv="expires" content="0">
		<meta http-equiv="pragma" content="no-cache">
		<meta http-equiv="cache-control" content="no-cache">
		<!--禁止缓存-测试时用-->
		<!--禁止禁止识别电话号码和邮件-->
		<meta name="format-detection" content="telephone=no, email=no" />
		<!--禁止禁止识别电话号码和邮件-->
		<!--x5内核浏览器包括：QQ浏览器，qq,微信内置的浏览器（ 竖屏显示、以及全屏显示）-->
		<meta name="x5-orientation" content="portrait" />
		<meta name="x5-fullscreen" content="true" />
		<!--x5内核浏览器包括：QQ浏览器，qq,微信内置的浏览器（ 竖屏显示、以及全屏显示）-->
		<!--UC浏览器竖屏显示和全屏显示-->
		<meta name="screen-orientation" content="portrait">
		<meta name="full-screen" content="yes">
		<!--UC浏览器竖屏显示和全屏显示-->
		<meta name="viewport" content="width=device-width,initial-scale=1.0,minimum-scale=1.0,maximum-scale=1.0,user-scalable=no" />
		<title>1px边框</title>
		<style type="text/css">
.u-1px {
  position: relative;
  width: 100px;
  height: 100px;
}

.u-1px::after {
  content: ' ';
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  border: 1px solid #000;
  box-sizing: border-box;
}

@media (-webkit-device-pixel-ratio: 1.5) {
  .u-1px::after {
    content: ' ';
    position: absolute;
    left: 0;
    top: 0;
    width: 150%;
    height: 150%;
    border: 1px solid #000;
    transform: scale(0.66666);
    transform: -origin: left top;
    box-sizing: border-box;
  }
}

@media (-webkit-device-pixel-ratio: 2) {
  .u-1px::after {
    content: ' ';
    position: absolute;
    left: 0;
    top: 0;
    width: 200%;
    height: 200%;
    border: 1px solid #000;
    transform: scale(0.5);
    transform: -origin: left top;
    box-sizing: border-box;
  }
}

		</style>
	</head>

	<body>
		<div class="u-1px">

		</div>
	</body>

</html>